Carbon ceramic composites and methods

Abstract

A composite article is comprised of coal dust, as defined herein, and a polymer derived ceramic material that is pyrolyzed in a substantially non-oxidizing atmosphere. For example, the composite article may be made of a mixture of the coal dust and polymer derived ceramic, from particles formed of a mixture of coal dust and polymer derived ceramic or from complex particle composites comprising a plurality of particles formed of a mixture of coal dust and polymer derived ceramic.

What is claimed is: 
     
       1. A ceramic composite article comprises:
 coal dust; 
 a polymer derived ceramic, wherein the coal dust is mixed with the polymer derived ceramic prior to pyrolyzation of the coal dust and the polymer derived ceramic to form a mixture of coal dust and the polymer derived ceramic; 
 prior to pyrolyzation of the mixture of coal dust and the polymer derived ceramic, the mixture of coal dust and the polymer derived ceramic is subjected to pressure to form a green composite article; and 
 the green composite article is pyrolyzed in a non-oxidizing atmosphere, such that at least some of the components of the coal dust are chemically reactive forming chemical bonds with the polymer derived ceramic material during the process of pyrolyzation, and the density of the green composite article increases during pyrolyzation. 
 
     
     
       2. The article of  claim 1 , wherein the coal dust and polymer derived ceramic are first formed into particles, a plurality of the particles are consolidated in a press to form the article, and the article is pyrolyzed in a non-oxidizing atmosphere. 
     
     
       3. The article of  claim 1 , wherein the coal dust and polymer derived ceramic are first formed into complex particles and a plurality of the complex particles are consolidated in a press to form the article, and the article is pyrolyzed in a non-oxidizing atmosphere. 
     
     
       4. The article of  claim 3 , wherein each of the complex particles comprise a plurality of particles made by mixing coal dust and a binder. 
     
     
       5. The article of  claim 4 , wherein the plurality of particles are pyrolyzed in a non-oxidizing atmosphere prior to consolidating the plurality of particles to form an article. 
     
     
       6. The article of  claim 5 , wherein the plurality of particles are consolidated by mixing the plurality of particles within a matrix comprised of carbon dust and polymer derived ceramic. 
     
     
       7. The article of  claim 6 , wherein the consolidated plurality of particles and the matrix are re-pyrolyzed in a non-oxidizing atmosphere. 
     
     
       8. The article of  claim 4 , wherein a coating is applied to the surface of the complex particles prior to consolidating the plurality of the complex particles to form the article. 
     
     
       9. A method of forming a ceramic composite article comprising:
 mixing coal dust and a polymer derived ceramic to form a mixture prior to any pyrolyzation of the coal dust or a polymer that forms the polymer derived ceramic; 
 subjecting the mixture to a pressure in a press to form a green composite article; and 
 pyrolyzing the green composite article in a non-oxidizing atmosphere, wherein at least some of the components of the coal dust are chemically reactive forming chemical bonds with the polymer derived ceramic material during the process of pyrolyzation, and the density of the green composite article increases during pyrolyzation. 
 
     
     
       10. The method of  claim 9 , further comprising a step of forming particles of coal dust and polymer derived ceramic first, then heating the particles of coal dust and polymer derived ceramic prior to the step of subjecting the mixture to a pressure; and
 consolidating a plurality of the particles into a press to form the green composite article prior to the step of pyrolyzing. 
 
     
     
       11. The method of  claim 10 , wherein the plurality of particles are first consolidated into a complex particle comprising a plurality of particles comprising coal dust mixed with the polymer of the polymer derived ceramic and a binder. 
     
     
       12. The method of  claim 11 , further comprising a step of mixing coal dust and the polymer of the polymer derived ceramic to form the binder, prior to consolidating the plurality of particles into a complex particle. 
     
     
       13. The method of  claim 12 , wherein the plurality of particles are pyrolyzed prior to consolidating the plurality of particles into complex particles. 
     
     
       14. The method of  claim 12 , wherein the plurality of particles are not pyrolyzed prior to consolidating the plurality of particles into complex particles. 
     
     
       15. The method of  claim 14 , wherein the complex particles are pyrolyzed prior to consolidating the complex particles. 
     
     
       16. The method of  claim 15 , wherein the complex particles are mixed with a binder prior to consolidating the complex particles into the shape of the article. 
     
     
       17. The method of  claim 16 , wherein the binder is prepared by mixing coal dust and a polymer derived ceramic, wherein the polymer derived ceramic may be the same polymer derived ceramic or a different polymer derived ceramic. 
     
     
       18. The method of  claim 17 , wherein the polymer derived ceramic is the same polymer derived ceramic. 
     
     
       19. The method of  claim 18 , further comprising a step of coating the complex particles with a coating prior to consolidating the plurality of the complex particles to form the article. 
     
     
       20. The method of  claim 9 , wherein the step of pyrolyzation comprises transforming kaolite and illite within the coal dust to silica and alumina.